Humidity-sensitive element



July 19, 1955 w. JOHNSON ET AL 2,713,625

HUMIDITY-SENSITIVE ELEMENT Filed April 29, 1953 EARL R. KEBBO/V and ROBERT W JOHNSON I INVENTORS .47'7'0 EYS 2,713,625 nUMinirY-sENstTn E ELEMENT Robert W. Johnson, Roselle, and Earl R. Kebbon, Chatham, N. .1 assignors to Weston Electrical Instrument Corporation, Newark, N. J., a corporation of New Jersey Application April 29, 1953, Serial No. 351,798 3 Claims. (Ci. 201-63) This invention relates to a humidity-sensitive element adapted for connection to an electrical circuit for the purpose of determining the relative humidity or moisture content of a medium.

While our humidity-sensitive device is suitable for general application the form to be described in detail here inbelow is particularly adapted for use in the determi nation of the moisture content within a sealed container and to this end the tate its installation on the container.

An object of this invention is the provision of a humidity-sensitive device that is economical to produce, readily installed in a sealed container and in which the actual sensitive material is protected against damage.

An object of this invention is the provision of a humidity-sensitive device adapted for connection in an electrical circuit and comprising a body of insulating material having a recess therein and a tapered shank adapted to be force-fitted in a hole in a container wall, a sensitive film disposed within the recess, of the type which changes its resistance with moisture, a pair of contact elements connected to said film and extending through the tapered shank, and locking means for securing the body to the container.

These and other objects and advantages will become apparent from the following description when taken with the accompanying drawings. it will be understood the drawings are for purposes of illustration and are not to be construed as defining the scope or limits of the invention, reference being had for the latter purpose to the appended claims.

in the drawings wherein like reference characters denote like parts in the several views:

Figure l is a top view of a humidity-sensitive device made in accordance with this invention;

Figure 2 is a side view of the device, with a portion broken away to show the disposition of the sensitive film and associated contacts;

Figure 3 is an exploded, isometric view of the device; and

Figure 4 is a front elevation of a container with a portion of the wall broken away to show the humiditysensitive device attached to the container cover.

As shown in Figures 1, 2 and 3, the device comprises a base member of insulating material, preferably of polyethylene plastic, comprising a body portion 16 and an integral, tapered shank 11. The body portion includes an axial recess 12. A circular disc 13 comprises the sensing film. Such disc preferably is made of regenerthin, of silver, gold, etc., painting or vacuum metalizing to form the spaced electrodes 14, 15. Those skilled in this art will understand that the electrical resistance between the electrodes 14 of such resistance variations can be controlled by vary- By connecting Z,?'l3,625 Patented July 19, 1955 the electrodes in an appropriate electrical circuit including an indicating instrument and a source of electrical energy the resistance variations, brought about by changes in the moisture content, will result in correcalibrated directly in terms of moisture content or percent humidity. The disc 13 is provided with a pair of holes l6, 17 which are adapted for alinement with the holes 13, 19 passing through the shank 11 to accommodate the headed connecting pins 26, 21. be pointed out that the member, are under-size so that the connecting pins 20, ,1 must be forced therethrough. Consequently, when thereof estabwhole. We have found that a mechanical contact between the head of the connecting pins and the underlying conducting film is satisfactory for most purposes. How ever, in some desirable to paint over the pin head and the conducting film with a suitable conductive paint thereby providing a more uniform and permanent electrical continuity between these members.

in Figure 4 there is shown a container 25 provided with a cover 26. in order to install our humidity-sensitive element on such container it is only necessary to provide a hole in the container wall, said hole having a diameter slightly greater than the minimum diameter of the tapered shank ll of the humidity-sensitive device. Actually, the amount of taper on the shank 11 is slight whereby the shank can be forced into the hole by finger pressure, yet the shank elfectively seals the hole thereby retaining the sealed or mo1sture-tight character of the container.

It will be noted that the connection pins 20, 21 are accessible externally of the container whereby the device can be connected in an appropriate electrical circuit that in eludes a suitably-calibrated indicating instrument.

indicating instrument. scale may be calibrated moisture content.

instrument of percent will under- Consequently, the directly in terms Those skilled in this art to protect by L forth in the following claims.

We claim:

1. A humiditysensitive member sulator member including a body portion and a tapered shank,

electrodes.

2. The invention as recited in claim 1 wherein the film member is a regenerated cellulose and said electrodes References Qiteal in the file of this patent UNlTED STATES PATENTS Allen Blodgett et al.

Nov. 11, 1930 Ian. 10, 1950 

